Translucent sheets

ABSTRACT

A translucent sheet is made of a textile net middle layer that is between two cover layers made of translucent films. In the middle layer, areas of the mesh run at an angle to the main direction of stress. In addition, there are stabilizing threads that run in the main direction of stress and are bonded to the knots of the textile net middle layer and give the structure of the middle layer particular strength in the main direction of stress.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention concerns a translucent sheet laminatedarticle comprising a textile net middle layer between two cover layerseach composed of translucent film.

[0003] 2. The Prior Art

[0004] Translucent sheets are used for tents, marquees, constructionsheeting or roofing paper. Products that are very mechanically stableconsist of several layers. The layered structure comprises a textile,net-like middle layer and two cover layers that enclose the textilemiddle layer. The textile middle layer provides mechanical stability.The net-like structure also allows light to pass through. The two coverlayers made of transparent films fix the textile net-like middle layerand seal against water and wind.

[0005] To absorb force in the primary direction of stress, the fibers ofthe textile, net-like middle layer must extend in the main direction ofstress. During production, particularly high force arises in thedirection of production. However, force can also arise when the finishedsheet is used that may be concentrated in one particular direction. Suchforce can result e.g. from wind or precipitation.

[0006] Meeting the mechanical requirements has limited the design of thenetwork. The design has therefore been limited to rectangular and squaremeshes. This design is insufficient for decorative products because themesh is visible due to the translucence of the sheet.

SUMMARY OF THE INVENTION

[0007] It is an object of the present invention to provide an improvedtranslucent sheet that allows greater freedom in designing the meshwhile retaining mechanical stability.

[0008] The above object is achieved by providing a translucent sheetlaminated article comprising a top cover layer made of a translucentfilm; a bottom cover layer made of a translucent film; a textile netmiddle layer that is between said two cover layers having areas of amesh of the textile net middle layer which are at an angle to a maindirection of stress, and said middle layer having stabilizing threadsaligned with the main direction of stress, and said stabilizing threadsare bonded to areas or knots of the textile net middle layer that run inthe same direction as said threads.

[0009] In the laminated article according to the invention, the mesh canhave any design. When areas of the mesh of the textile net middle layerare at an angle to the main direction of stress and cannot thereforeabsorb force in the main direction of the stress, the stabilizationthreads in the main direction of force absorb the force completely. Thisalso means that the mesh shape intended by the designer is retainedduring production. Hence the mesh is not distorted by forces arising inproduction.

[0010] The sandwich structure of the textile net middle layer and thecover layers yields a basic mechanical strength after production. Thestabilizing threads increase strength in the direction in which theyrun. When there is a main direction of stress, the translucent sheet isaligned so that the stabilizing threads run in the main direction ofstress.

[0011] In one embodiment of the invention, the cross-section of thefibers forming the mesh is greater than the cross-section of thestabilizing fibers. The bond of the fibers forming the mesh to the coverlayers therefore becomes tighter. At the same time, the stabilizingfibers become less visually prominent than the fibers forming the mesh.

[0012] The mesh can be polygonal. This produces a type of honeycombpattern in which parts of the mesh form parts of adjacent mesh. Thisproduces a favorable ratio between the open and hence translucent areasof the mesh and the areas occupied by the fibers of the mesh. Aparticularly high basic strength results from the bond between thetextile net middle layer and the cover layers in all directions withinthe plane of the sheet.

[0013] The mesh width can be 2 mm to 10 mm. This dimension represents anoptimum compromise between light permeability and mechanical strength.

[0014] The textile net middle layer preferably comprises a knit. Thistype of textile yields a particularly good bond between the individualfibers forming the mesh and the stabilizing fibers.

[0015] The fibers of the mesh can be a multitwisted monofilament yarn.This improves the bonding of the knots of the mesh to themselves and thebond between the fibers of the textile middle layer and the coverlayers.

[0016] The material of the textile net middle layer can comprisesynthetic raw materials, preferably polyester, polyamide, polyaramide,polyimide or mixtures thereof. These raw materials have a reducedtendency to stretch and yield under tension. This ensures that the sheetretains its form and shape under stretching.

[0017] The material of the textile net middle layer can be colored. Thisallows the textile structure to be visually distinguished from thestabilizing threads so that the stabilizing threads become practicallyinvisible. In addition, the overall sheet can be in the form of anornamental structure.

[0018] The textile net middle layer can be 0.3-0.6 mm thick, andpreferably 0.35 mm thick. This dimension represents the best compromisebetween mechanical strength and flexibility, i.e., its bending orfolding property.

[0019] The two cover layers are preferably comprised by a thermoplasticmaterial, and they are melted together through the meshes of the textilenet middle layer to form the laminated article. This produces a veryprecise geometric structure of the sheet that ensures that the textilenet middle layer assumes a precise position between the two coverlayers. In addition, a tight bond between the cover layers is ensured.

[0020] The thermoplastic can be made with a calender or extruder. Thisembodiment produces a very homogenous cover layer with a uniformthickness.

[0021] The thermoplastic material is preferably comprised by soft PVC,thermoplastic olefins or polyurethane. This material is particularlyyielding and adheres well to provide a tight bond to the textilematerial.

[0022] In another embodiment, it is possible for at least the top coverlayer to contain antioxidants and UV absorbers and/or IR absorbers. Thisensures long life while maintaining the useful properties even when thesheet is continuously exposed to the weather and to sunlight.

[0023] In a further embodiment, one of the cover layers can contain acolor agent, such as dyes and/or pigments. It is also possible for thetwo cover layers to contain different dyes and/or pigments. In additionto decorative possibilities for the sheet, the light permeability, orthe color of the transmitted light and the permeability to orabsorption/reflection of IR or UV rays can be influenced.

[0024] The cover layers can be 0.3-0.45 mm thick and preferably 0.35 mmthick depending on the middle layer. This dimension for the thickness ofthe cover layers provides sufficient cover and encasing for the fibersof the middle layer.

[0025] In a further embodiment, at least one of the cover layers canhave an embossed surface. This increases the construction possibilitiesof the sheet and influences the stability and bendability of the sheet.

[0026] In another embodiment, the top cover layer can have an additionaltranslucent varnish coating or layer thereon. This varnish layer canprotect the cover layer. In particular, it protects againstmicroorganisms that can collect on the surface under the influence ofweather in the form of moss or algae.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Other objects and features of the present invention will becomeapparent from the following detailed description considered inconnection with the accompanying drawing which discloses severalembodiments of the present invention. It should be understood, however,that the drawing is designed for the purpose of illustration only andnot as a definition of the limits of the invention.

[0028] In the drawing, wherein similar reference characters denotesimilar elements throughout the several views:

[0029]FIG. 1 shows a cross-section view of a translucent sheet laminatedarticle according to the invention; and

[0030]FIG. 2 shows a top view of the translucent sheet of FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0031] Turning now in detail to the drawings, FIG. 1 shows across-section of a laminated article 1 from top to bottom. Article 1comprises a top cover layer 10 made of a translucent thermoplastic film,a middle layer 12 comprising a textile, net-like knit, and a bottomcover layer 14 made of a translucent, thermoplastic film. The middlelayer 12 is made of a mesh whose fibers 18 are formed by a multitwistedmonofilament yarn. In addition, stabilizing threads 20 are knitted intothe yarn that are bonded to areas or knots 22 (FIG. 2) of the mesh 16 ofthe textile, net-like middle layer 12 that run in the same direction.The section is transverse to the stabilizing threads 20 in the drawing.The main direction of stress 26 of the material therefore also runstransverse to the represented section plane.

[0032] The top and bottom cover layers 10,14 are melted together intothe gaps of the middle layer 12 to produce the laminated article 1. Theycompletely enclose the fibers 18 and the stabilizing threads 20. Thetextile middle layer 12 is therefore completely integrated into thesheet. The top and/or bottom cover layers 10,14 can be colored. Hence,pigments can be used within the cover layers 10,14 to create the colors.The pigments can be translucent or light-absorbing or light-reflecting.The top cover layer 10 also has a varnish coating 24. The surface of thecover layers 10,14 have a textured structure that results from thelayers 10,14 adapting to the structure provided by the textile netmiddle layer 12.

[0033]FIG. 2 shows a top view of the translucent sheet where the textilenet middle layer 12 is visible through the top cover layer and can berecognized. The structure of the mesh 16 of the middle layer 12 ispreferably hexagonal, such as a honeycomb structure. The stabilizingthreads 20 that run in the main direction of stress 26 run through themesh 16. Threads 20 are knit with the areas of the mesh 16 that run inthe same direction, or threads 20 are bonded as knots 22. The mesh 16 istightly bonded to the stabilizing threads 20. In addition, it can beseen that the diameter and cross-section of the fibers 18 of the mesh 16is greater than the diameter and cross-section of the stabilizingthreads 20.

[0034] The laminated article of the invention is particularly useful forvehicles as a translucent folding roof or as a sunroof. The increasedmechanical strength along the direction of the stabilizing threads 20 isadvantageous. The increased strength helps absorb force that arises whenclosing the folding roof, and absorbs force from suction due to windduring travel without the material stretching undesirably.

[0035] Accordingly, while a few embodiments of the present inventionhave been shown and described, it is to be understood that many changesand modifications may be made thereunto without departing from thespirit and scope of the invention as defined in the appended claims.

What is claimed is:
 1. A translucent sheet laminated article comprisinga top cover layer made of a translucent film (10); a bottom cover layermade of a translucent film (14); a textile net middle layer (12) that isbetween said two cover layers (10,14) having areas of a mesh (16) of thetextile net middle layer (12) which are at an angle to a main directionof stress (26), and said middle layer (12) having stabilizing threads(20) aligned with the main direction of stress (26) are bonded to areasor knots (22) of the textile net middle layer that run in the samedirection as said threads (20).
 2. A translucent sheet according toclaim 1 , wherein said mesh is formed by fibers (18); and wherein across-section of fibers (18) forming the mesh (16) is greater than across-section of the stabilizing threads (20).
 3. A translucent sheetaccording to claim 1 , wherein the mesh (16) is polygonal.
 4. Atranslucent sheet according to claim 1 , wherein the mesh (16) is 2-10mm wide.
 5. A translucent sheet according to claim 1 , wherein thetextile net middle layer (12) is a knit.
 6. A translucent sheetaccording to claim 2 , wherein the fibers (18) of the mesh (16) comprisemultitwisted monofilament yarn.
 7. A translucent sheet according toclaim 1 , wherein the textile net middlelayer (12) comprises a syntheticraw material selected from the group consisting of polyester, polyamide,polyaramide, polyimide, and mixtures thereof.
 8. A translucent sheetaccording to claim 1 , wherein the textile net middle layer (12)contains a color agent.
 9. A translucent sheet according to claim 1 ,wherein the textile net middle layer (12) has a thickness of 0.3-0.6 mm.10. A translucent sheet according to claim 1 , wherein each of the twocover layers (10,14) comprises a thermoplastic material, and said coverlayers are melted together through the mesh (16) of the textile netmiddle layer (12).
 11. A translucent sheet according to claim 10 ,wherein the thermoplastic material is created with a calender or anextruder.
 12. A translucent sheet according to claim 10 , wherein thethermoplastic material is selected from the group consisting of softPVC, thermoplastic olefins, and polyurethane.
 13. A translucent sheetaccording to claim 10 , wherein at least the top cover layer contains anantioxidant, a UV absorber or an IR absorber.
 14. A translucent sheetaccording to claim 1 , wherein at least one of said cover layers (10,14)contains a color agent selected from the group consisting of a dye and apigment.
 15. A translucent sheet according to claim 14 , wherein one ofthe two cover layers (10,14) contain a different dye or a differentpigment from that contained in the other cover layer.
 16. A translucentsheet according to claim 1 , wherein each of the cover layers (10, 14)has a thickness of 0.3-0.45 mm depending on the middle layer (12).
 17. Atranslucent sheet according to claim 1 , wherein at least one of thecover layers (10,14) has an embossed surface.
 18. A translucent sheetaccording to claim 1 , wherein the top cover layer (10) has atranslucent varnish coating (24).
 19. A translucent sheet according toclaim 1 , comprising a translucent folding roof for automobiles.
 20. Atranslucent sheet according to claim 1 , wherein the textile net middlelayer (12) has a thickness of 0.35 mm; and wherein each of the coverlayers (10, 14) has a thickness of 0.35 mm.